SELECT
	O.DEPT_CODE AS DEPT_CODE
	,D.DEPT_NAME 
FROM
	TBL_ORDERS AS O
	LEFT OUTER JOIN TBL_DEPT AS D
		ON D.DEPT_CODE = O.DEPT_CODE
UNION

SELECT
	S.DEPT_CODE AS DEPT_CODE
	,D.DEPT_NAME 
FROM
	TBL_SALES AS S
	LEFT OUTER JOIN TBL_DEPT AS D
		ON D.DEPT_CODE = S.DEPT_CODE;